: Maybe because it gives the flood an oppurtunity to upload the virus to
: Cortana?

I'm not really sure if the Flood have a long enough life-span to have been able to infect the body of a Forerunner (thereby giving that Flood the knowledge of that Forerunner), because, as we know, the Forerunner are extinct, because they were an ancient civilization. Even if a Flood-controlled Covenant were to make it to the computer systems, I don't think that it would have the knowledge of the system to be able to both a) make a virus and then b) upload it to the construct that he didn't know would be there anyway. It would take a Forerunner to be able to get into the system and make the virus, unless you think that 343 somehow gave the Flood the information to do this. Anyway, this is what I think. As to Cortana being rampant, or a Flood getting into the Longsword, I haven't actually debated yet. I'll get there